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*** Preliminary and in Preprint, but if this observation is correct and commonplace many pieces of the contagion puzzle would begin to fit. – Ralph Turchiano

Study Quote “Interestingly, in 2 (487941 and 487250) of the 3 viral culture negative individuals for which we collected both saliva and nasal samples, viral RNA was detectable in saliva for 5 to 10 days while remaining either undetectable (487941) or detectable at very low level for 2 days (487250) in nasal swabs. These data suggest that in 2 of the 4 fully vaccinated individuals for which both saliva and nasal swabs were collected, infection was initially established within the oral cavity or other saliva-exposed tissue site and was restricted from disseminating to the nasal passages. We did not observe a similar restriction of virus to saliva across 60 non-vaccinated individuals that we examined in a previous report 7 suggesting that severe compartmentalization and tissue-restriction of virus may be a unique feature of vaccine breakthrough infections.

Longitudinal analysis of SARS-CoV-2 vaccine breakthrough infections reveal limited infectious virus shedding and restricted tissue

Ruian Ke, Pamela Martinez, RebeccaLee Smith, Laura Gibson, Chad Achenbach, Sally McFall, Chao Qi, Joshua Jacob, Etienne Dembele, Camille Bundy, Lacy M Simons, Egon A Ozer, JuddF. Hultquist, Ramon LorenzoRedondo, Anita Opdycke, Claudia Hawkins, Robert Murphy, Agha Mirza, Madison Conte, Nicholas Gallagher, Chun Huai Luo, Junko Jarrett, Abigail Conte, Ruifeng Zhou, Mireille Farjo, Gloria Rendon, Christopher J. Fields, Leyi Wang, Richard Fredrickson, Melinda Baughman, Karen Chiu, Hannah Choi, Kevin Scardina, Alyssa Owens, John Broach, Bruce Barton, Peter Lazar, Matthew L Robinson, Heba Mostafa, Yukari C Manabe, Andrew Pekosz, David McManus, Christopher B Brooke

medRxiv 2021.08.30.21262701; doi:

This article is a preprint and has not been certified by peer review [what does this mean?]. It reports new medical research that has yet to be evaluated and so should not be used to guide clinical practice.


The global effort to vaccinate people against SARS-CoV-2 in the midst of an ongoing pandemic has raised questions about the nature of vaccine breakthrough infections and the potential for vaccinated individuals to transmit the virus. These questions have become even more urgent as new variants of concern with enhanced transmissibility, such as Delta, continue to emerge. To shed light on how vaccine breakthrough infections compare with infections in immunologically naive individuals, we examined viral dynamics and infectious virus shedding through daily longitudinal sampling in a small cohort of adults infected with SARS-CoV-2 at varying stages of vaccination. The durations of both infectious virus shedding and symptoms were significantly reduced in vaccinated individuals compared with unvaccinated individuals. We also observed that breakthrough infections are associated with strong tissue compartmentalization and are only detectable in saliva in some cases. These data indicate that vaccination shortens the duration of time of high transmission potential, minimizes symptom duration, and may restrict tissue dissemination.

Competing Interest Statement

CBB and LW are listed as inventors on a pending patent application for the saliva RTqPCR test used in this study.

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